2. Carbohydrates
glucose provides energy for the brain and ½
of energy for muscles and tissues
glycogen is stored glucose
glucose is immediate energy
glycogen is reserve energy
3. Carbohydrates
all plant food
milk
carbohydrates are not equal
– simple carbohydrates
– complex carbohydrates
10. Disaccharides
pairs of the monosaccharides
– glucose is always present
– 2nd of the pair could be fructose, galactose
or another glucose
– taken apart by hydrolysis
– put together by condensation
– hydrolysis and condensation occur with all
energy nutrients
– maltose, sucrose, lactose
16. Complex Carbohydrates
polysaccharides
– glycogen and starch
built entirely of glucose
– fiber
variety of monosaccharides and other
carbohydrate derivatives
17. Glycogen
limited in meat and not found in plants
– not an important dietary source of
carbohydrate
BUT
– all glucose is stored as glycogen
– long chains allow for
hydrolysis and release
of energy
19. Fiber
structural parts of plants
– found in all plant derived food
bonds of fibers cannot be broken down
during the digestive process
– minimal or no energy available
21. Fiber Characteristics
soluble fibers, viscous, fermentable
– easily digested by bacteria in colon
– associated with protection against heart
disease and diabetes
lower cholesterol and glucose levels
– found in legumes and fruits
22. Fiber
insoluble and not easily fermented
– promote bowel movements
– alleviate constipation
– found in grains and vegetables
23. DRI and Fiber
distinguish fibers by source
– dietary fibers: naturally in intact plants
– functional fibers: extracted from plants or
manufactured
– total fiber: sum of the 2
24. Carbohydrate Digestion
break down into glucose
– body is able to absorb and use
large starch molecules
– extensive breakdown
disaccharides
– broken once
monosaccharides
– don’t need to be broken down
25. Carbohydrate Digestion
begins in mouth
– chewing releases saliva
– enzyme amylase hydrolyzes starch to
polysaccharides and maltose
stomach
– no enzymes available to break down
starch
– acid does some breakdown
– fibers in starch provide feeling of fullness
26. small intestine
– majority of carbohydrate digestion
takes place here
– pancreatic amylase reduces carbs to
glucose chains or disaccharides
– specific enzymes finish the job
maltase
–maltose into 2 glucose
sucrase
–sucrose into glucose and fructose
lactase
–lactose into glucose and
galactose
27. large intestine
– 1-4 hours for sugars and
starches to be digested
– only fibers remain
attract water, which
softens stool
– bacteria ferment some fibers
water, gas, short-chain
fatty acids (used for
energy)
28. Carbohydrate Absorption
glucose can be absorbed in the mouth
majority absorbed in small intestine
– active transport
glucose and galactic
– facilitated diffusion
fructose
smaller rise in blood glucose
29. Lactose Intolerance
more lactose is consumed than can be
digested
– lactose molecules attract water
cause floating, abdominal discomfort,
diarrhea
– intestinal bacteria feed on undigested
lactose
produce acid and gas
30. Lactose Intolerance
age, damage, medication, diarrhea,
malnutrition
management requires dietary change
– 6 grams (1/2 cup) usually tolerable
– take in gradually
– hard cheeses & cottage cheese
– enzyme drops or tablets
lactose free diet is extremely difficult to
accomplish
31.
32. Carbohydrate Metabolism
1/3 of body’s glycogen is stored in liver
– released as glucose to bloodstream
1. eat – intake glucose
2. liver condenses extra glucose to glycogen
3. blood glucose falls
4. liver hydrolyzes glycogen to glucose
Glycogen is bulky, so we store only so much:
short term energy supply
Fat is the long term energy supply.
33. Glucose for Energy
enzymes break apart glucose – yielding
energy
inadequate supply of carbohydrates
– ketone bodies (fat fragments) are an
alternate energy source during starvation
– excess ketones can lead to ketosis:
imbalance of acids in body
minimum of 50 – 100 grams of carbs/day
are needed to avoid ketosis
34. Glucose Homeostasis
maintaining an even balance of glucose is
controlled by insulin and glucagon
– insulin
moves glucose into the blood
– glucagon
brings glucose out of storage
35. maintaining balance
– balanced meals at regular intervals
fiber and some fat slow the digestive
process down
glucose gets into the blood slow and
steady
36. Intestine 1
When a person eats,
Maintaining blood glucose rises.
Blood
Glucose Pancreas
2
High blood glucose stimulates
Homeostasis the pancreas to release insulin.
Insulin
3 Insulin stimulates the uptake of
glucose into cells and storage
as glycogen in the liver and
Liver muscles. Insulin also stimulates
the conversion of excess
glucose into fat for storage.
Fat cell Muscle
4
As the body's cells use
glucose, blood levels decline.
Pancreas 5 Low blood glucose stimulates
the pancreas to release
Glucagon glucagon into the bloodstream.
6 Glucagon stimulates liver
cells to break down glycogen
Glucose and release glucose into the
blood.a
Insulin
Glucagon
Liver
Glycogen
a
The stress hormone
epinephrine and other hormones 7 Blood glucose begins to
also bring glucose out of storage. rise.
37. Imbalance
diabetes
– after food intake, blood glucose rises and
is not regulated because insulin is
inadequate
hypoglycemia
– blood glucose drops dramatically
too much insulin, activity, inadequate
food intake, illness
diet adjustment includes fiber-rich carbs
and protein
38. Glycemic Index
way of classifying
food according to
their ability to raise
blood glucose
much controversy
39. Sugar
½ comes from natural sources, ½ from
refined and added
– sucrose, corn syrup, honey
excess can lead to nutrient deficiencies
and tooth decay
– empty calories
– sugar and starch break down in the
mouth
41. Starch and Fiber
diet that includes starch, fiber and natural
sugars
– whole grains, vegetables, legumes, fruits
may protect against heart disease and
stroke
reduces the risk of type 2 diabetes
enhances the health of the large
intestine
can promote weight loss
42. Starch and Fiber
starch intake
– 45-65%
– 225 – 325 grams (DV is 300
grams)
– 900-1300 kcal/2000 kcal
– RDA is 130 grams
fiber intake
– Daily Value is 25 grams/2000
kcal
43.
44.
45. Groceries
grains: 1 serving = 15 grams
vegetables
– ½ cup starchy = 15 grams
– ½ cup nonstarchy = 5 grams
fruit: 1 serving = 15 grams
milk: 1 cup = 12 grams
meat: none or little
legumes: ½ cup = 15 grams
46. Artificial Sweeteners
help keep sugar and energy intake down
anything we eat has FDA approval
– saccharin
– aspartame
– acesulfame potassium
– sucralose
– neotame
47.
48. Sugar Replacers
sugar alcohols
– provide bulk and sweetness
cookies, gum, candy, jelly
– do contain minimal kcal
– low glycemic response
absorbed slowly
– do not cause dental caries